While this fusion transcript is relatively specific to one pediatric brain tumor, the pilocytic astrocytoma (up to 70 % of the cases), a subsequent study of 1320 nervous system tumors revealed exceptionally high rates of BRAF V600E mutations in pleomorphic xanthoastrocytomas (PXA) WHO grade II (66 %) and III (65 %) as well as gangliogliomas WHO grade I (18 %) and III (50 %). The gene discussed is BRAF; the disease is brain neoplasm.